Imaging of Biliary Tree Abnormalities.

Pathologic conditions of the biliary system, although common, can be difficult to diagnose clinically. Challenges in biliary imaging include anatomic variants and the dynamic nature of the biliary tract, which can change with age and intervention, blurring the boundaries of normal and abnormal. Choledochal cysts can have numerous appearances and are important to diagnose given the risk of cholangiocarcinoma potentially requiring surgical resection. Choledocholithiasis, the most common cause of biliary dilatation, can be difficult to detect at US and CT, with MRI having the highest sensitivity. However, knowledge of the imaging pitfalls of MRI and MR cholangiopancreatography is crucial to avoid misinterpretation. Newer concepts in biliary tract malignancy include intraductal papillary biliary neoplasms that may develop into cholangiocarcinoma. New paradigms in the classification of cholangiocarcinoma correspond to the wide range of imaging appearances of the disease and have implications for prognosis. Accurately staging cholangiocarcinoma is imperative, given expanding curative options including transplant and more aggressive surgical options. Infections of the biliary tree include acute cholangitis or recurrent pyogenic cholangitis, characterized by obstruction, strictures, and central biliary dilatation. Inflammatory conditions include primary sclerosing cholangitis, which features strictures and fibrosis but can be difficult to differentiate from secondary causes of sclerosing cholangitis, including more recently described entities such as immunoglobulin G4-related sclerosing cholangitis and COVID-19 secondary sclerosing cholangitis. The authors describe a wide variety of benign and malignant biliary tract abnormalities, highlight differentiating features of the cholangitides, provide an approach to interpretation based on the pattern of imaging findings, and discuss pearls and pitfalls of imaging to facilitate accurate diagnosis. ©RSNA, 2024 Supplemental material is available for this article.

Management of iatrogenic perforations during endoscopic interventions in the hepato-pancreatico-biliary tract.

Endoscopic retrograde cholangiopancreaticography (ERCP) and endoscopic ultrasound (EUS) guided interventions are among the most challenging procedures performed by interventional endoscopists and are associated with a significant risk of complications. Early recognition and classification of perforations allows immediate therapy which improves clinical outcomes. In this article we review the different aspects of iatrogenic perforations associated with pancreatico-biliary interventions, elucidating risk factors, diagnostic challenges and the latest therapeutic interventions.

Booster administration of Tc-99m PMT for delayed static imaging in patients with biliary atresia.

OBJECTIVE: Tc-99m N-pyridoxyl-5-methyl-tryptophan (PMT) hepatobiliary scintigraphy has high diagnostic performance for biliary atresia. Our hospital implements standard Tc-99m PMT administration followed by a 6 h static imaging review; booster doses are given in cases requiring 24 h delayed scans. This study aimed to evaluate the diagnostic performance of this method. METHODS: A total of 37 pediatric patients who underwent Tc-99m PMT biliary scintigraphy were classified into the surgically-diagnosed biliary atresia or non-biliary atresia groups. The absence of tracer accumulation in the small bowel was considered a hepatobiliary scintigraphic diagnosis of biliary atresia. The Clopper-Pearson method was used to calculate the 95% confidence intervals (CIs) for determining the diagnostic accuracy, negative predictive value, positive predictive value, sensitivity, and specificity of Tc-99m PMT biliary scintigraphy. RESULTS: Among the 37 patients, 12 were classified into the diagnosis of biliary atresia group. Regarding biliary scintigraphy findings, 16 of 37 patients demonstrated tracer accumulation in the small bowel within 6 h of testing. These cases were diagnosed as non-biliary atresia, requiring no further testing or booster administration. In contrast, 21 patients underwent delayed testing requiring booster administration, which revealed 13 without tracer excretion and 11 who were diagnosed with biliary atresia. Among the eight patients with tracer accumulation, only one was diagnosed with biliary atresia. Furthermore, two cases without tracer excretion and seven cases with tracer excretion were clinically diagnosed as non-biliary atresia. The diagnostic performance of our examination was as follows: a diagnostic accuracy of 91.9% (34/37; 95% CIs 78.0-98.3%), sensitivity of 91.6% (11/12; 95% CIs 61.5-99.8%), specificity of 92.0% (23/25; 95% CIs 74.0-99.0%), a positive predictive value of 84.6% (11/13; 95% CIs 54.6-98.0%), and a negative predictive value of 95.8% (23/24; 95% CIs 78.9-99.9%). CONCLUSIONS: Our protocol for Tc-99m PMT biliary scintigraphy using tracer booster administration demonstrated reliable diagnostic performance for biliary atresia. Notably, 43% of cases did not require booster administration, indicating that lesser radiation exposure may still yield comparable diagnostic accuracy.

Normal morphometry of the biliary tree in pediatric and adult populations: A systematic review and meta-analysis.

PURPOSE: This study aimed to characterise the normal morphometry of the biliary tree in pediatric and adult populations, through a systematic review and meta-analysis. METHODS: This study, conducted using the PRISMA guidelines and registered with PROSPERO, searched MEDLINE, EMBASE, SCOPUS and Web of Science databases up to October 2022, and updated to August 2023. Studies that reported extractable data on diameter and length of the right, left and common hepatic ducts (LHD, RHD and CHD), and common bile duct (CBD) were included. Quality of the included studies were assessed using the Anatomical Quality Assessment (AQUA) tool. Statistical analysis included subgroup analyses according to sex, age, geographical location, and imaging modality. RESULTS: In total, 60 studies were included, of which 44 studies reported adequate data for meta-analysis on 23,796 subjects. Overall, the pooled mean diameter of the CBD was 4.69 mm (95 % CI: 4.28-5.11). Significant differences were found between pediatric (1.32 mm, 95 % CI: 1.03-1.61) and adult (4.97 mm, 95 % CI: 4.67-5.27) subjects, as well as US (3.82 mm, 95 % CI: 3.15-4.49) and other imaging modalities, including MRI (6.21 mm, 95 % CI: 4.85-7.57) and ERCP (7.24 mm, 95 % CI: 6.08-8.40). The CBD diameter measured significantly larger distally (5.20 mm, 95 % CI: 4.60-5.80) than proximally (4.01 mm, 95 % CI: 3.51-4.51). CONCLUSIONS: The results obtained from this evidence-based study may guide the establishment of standardised reference values and ranges of the normal biliary tree in pediatric and adult populations and aid clinical understanding.

Determining the patency of biliary tracts in dogs with gallbladder mucocele using near-infrared cholangiography with indocyanine green.

Cholecystectomy is indicated for gallbladder mucoceles (GBM). Evaluating the patency of the biliary duct and precise biliary tree visualization is crucial for reducing the risk of compromised bile flow after surgery. Therefore, intraoperative cholangiography (IOC) is recommended during cholecystectomy to prevent biliary tract injury. Although indocyanine green (ICG) cholangiography has been extensively reported in human medicine, only one study has been conducted in veterinary medicine. Therefore, this study aimed to demonstrate the use of ICG for IOC to identify fluorescent biliary tract images and determine the patency of the common bile duct during cholecystectomy in dogs. This study comprised 27 dogs, consisting of 17 with gallbladder mucoceles (GBM) and 10 controls, specifically including dogs that had undergone elective cholecystectomy for GBM. ICG injection (0.25 mg/kg) was administered intravenously at least 45 minutes before surgery. During the operation, fluorescent images from cholangiography were displayed on the monitor and obtained in black-and-white mode for the comparison of fluorescence intensity (FI). The FI values of the gallbladders (GBs) and common bile duct (CBD) were measured using FI analyzing software (MGViewer V1.1.1, MetapleBio Inc.). The results demonstrated successful CBD patency identification in all cases. Mobile GBM showed partial gallbladder visibility, whereas immobile GBM showed limited visibility. Additionally, insights into the adequate visualization of the remaining extrahepatic biliary tree anatomy were provided, extending beyond the assessment of CBD patency and gallbladder intensity. Our study demonstrates the potential of fluorescent IOC using intravenous injection of ICG for assessing the patency of the cystic duct and common bile duct during cholecystectomy in patients with GBM, eliminating the need for surgical catheterization and flushing of the biliary ducts. Further research is warranted to investigate and validate the broader applicability of ICG cholangiography in veterinary medicine.

Three-dimensional magnetic resonance cholangiography is superior to two-dimensional single-shot magnetic resonance cholangiography for visualization and image quality of the feline and canine biliary tract: A postmortem study.

Magnetic resonance cholangiography (MRC) is an established diagnostic tool for noninvasive assessment of the biliary tract in humans. It has also been found to be feasible in companion animals, but no published studies have compared MRC sequences in veterinary medicine. The present study is part of a prospective, observational, analytical investigation on MR cholangiopancreatography performed on the donated bodies of 12 cats and eight dogs. The main aim of this study was to compare the images of 2D-SSh-TSE-MRC and 3D-TSE-MRC sequences for visualization and image quality of the feline and canine biliary tract. Both sequences are T2-weighted and noncontrast. Three independent readers scored the visibility of four segments of the biliary tract, namely the gallbladder (GB), cystic duct, common bile duct (CBD), and extrahepatic ducts, and the image quality of the two MRC sequences using five-point Likert scales. Wilcoxon signed-rank test was used to compare the scores between the MRC sequences separately for cats and dogs. Inter- and intraobserver agreements were measured using Gwet's AC2 with linear weighting. The 3D-TSE-MRC images were scored significantly higher than the 2D-SSh-TSE-MRC for both visibility and image quality (P < .001-.016 for cats, P = .008-.031 for dogs); the only exception was GB in dogs. In both cats and dogs, interobserver agreement for segment visibility and image quality ranged from slight to substantial in 2D-SSh-TSE-MRC and from poor to almost perfect in 3D-TSE-MRC. Most of the assessments (73% for segment visibility and 66% for image quality) had substantial to almost perfect intraobserver agreement. Findings from the current study support the use of 3D-TSE-MRC over 2D-SSh-TSE-MRC for evaluation of the feline and canine biliary tract, but further studies on live animals are warranted.

Percutaneous Ultrasound Cholangiography With Microbubbles in Children With Biliary Diseases.

ABSTRACT: The application of intracavity contrast-enhanced ultrasound in the evaluation of biliary disease has been confirmed valuable among pediatric population. This pictorial essay aims to demonstrate the role of percutaneous ultrasound cholangiography (PUSC) with microbubbles in the diagnosis of different pediatric biliary diseases in our center. The biliary system's morphologic characteristics in PUSC mode of neonatal hepatitis, biliary atresia, choledochal cysts, and biliary complications of hepatobiliary surgery are presented.

Intra-operative ultrasound assessment of the biliary tree during robotic cholecystectomy.

Image-guided assessment of bile ducts and associated anatomy during laparoscopic cholecystectomy can be achieved with intra-operative cholangiography (IOC) or laparoscopic ultrasound (LUS). Rates of robotically assisted cholecystectomy (RC) are increasing and herein we describe the technique of intra-corporeal biliary ultrasound during RC using the Da Vinci system. For intraoperative evaluation of the biliary tree during RC, in cases of suspected choledocholithiasis, the L51K Ultrasound Probe (Hitachi, Tokyo, Japan) is used. The extrahepatic biliary tree is scanned along its length, capitalising on the benefits of the full range of motion offered by the articulated robotic instruments and integrated ultrasonic image display using TileProTM software. Additionally, this technique avoids the additional time and efforts required to undock and re-dock the robot that would otherwise be required for selective IOC or LUS. The average time taken to perform a comprehensive evaluation of the biliary tree, from the hepatic ducts to the ampulla of Vater, is 164.1 s. This assessment is supplemented by Doppler ultrasound, which is used to fully delineate anatomy of the porta hepatis, and accurate measurements of the biliary tree and any ductal stones can be taken, allowing for contemporaneous decision making and management of ductal pathologies. Biliary tract ultrasound has been shown to be equal to IOC in its ability to diagnose choledocholithiasis, but with the additional benefits of being quicker and having higher completion rates. We have described our practice of using biliary ultrasound during robotically assisted cholecystectomy, which is ergonomically superior to LUS, accurate and reproducible.

Real-time continuous image guidance for endoscopic retrograde cholangiopancreatography based on 3D/2D registration and respiratory compensation.

BACKGROUND: It has been confirmed that three-dimensional (3D) imaging allows easier identification of bile duct anatomy and intraoperative guidance of endoscopic retrograde cholangiopancreatography (ERCP), which reduces the radiation dose and procedure time with improved safety. However, current 3D biliary imaging does not have good real-time fusion with intraoperative imaging, a process meant to overcome the influence of intraoperative respiratory motion and guide navigation. The present study explored the feasibility of real-time continuous image-guided ERCP. AIM: To explore the feasibility of real-time continuous image-guided ERCP. METHODS: We selected 2 3D-printed abdominal biliary tract models with different structures to simulate different patients. The ERCP environment was simulated for the biliary phantom experiment to create a navigation system, which was further tested in patients. In addition, based on the estimation of the patient's respiratory motion, preoperative 3D biliary imaging from computed tomography of 18 patients with cholelithiasis was registered and fused in real-time with 2D fluoroscopic sequence generated by the C-arm unit during ERCP. RESULTS: Continuous image-guided ERCP was applied in the biliary phantom with a registration error of 0.46 mm ± 0.13 mm and a tracking error of 0.64 mm ± 0.24 mm. After estimating the respiratory motion, 3D/2D registration accurately transformed preoperative 3D biliary images to each image in the X-ray image sequence in real-time in 18 patients, with an average fusion rate of 88%. CONCLUSION: Continuous image-guided ERCP may be an effective approach to assist the operator and reduce the use of X-ray and contrast agents.

BiTNet: Hybrid deep convolutional model for ultrasound image analysis of human biliary tract and its applications.

Certain life-threatening abnormalities, such as cholangiocarcinoma, in the human biliary tract are curable if detected at an early stage, and ultrasonography has been proven to be an effective tool for identifying them. However, the diagnosis often requires a second opinion from experienced radiologists, who are usually overwhelmed by many cases. Therefore, we propose a deep convolutional neural network model, named biliary tract network (BiTNet), developed to solve problems in the current screening system and to avoid overconfidence issues of traditional deep convolutional neural networks. Additionally, we present an ultrasound image dataset for the human biliary tract and demonstrate two artificial intelligence (AI) applications: auto-prescreening and assisting tools. The proposed model is the first AI model to automatically screen and diagnose upper-abdominal abnormalities from ultrasound images in real-world healthcare scenarios. Our experiments suggest that prediction probability has an impact on both applications, and our modifications to EfficientNet solve the overconfidence problem, thereby improving the performance of both applications and of healthcare professionals. The proposed BiTNet can reduce the workload of radiologists by 35% while keeping the false negatives to as low as 1 out of every 455 images. Our experiments involving 11 healthcare professionals with four different levels of experience reveal that BiTNet improves the diagnostic performance of participants of all levels. The mean accuracy and precision of the participants with BiTNet as an assisting tool (0.74 and 0.61, respectively) are statistically higher than those of participants without the assisting tool (0.50 and 0.46, respectively (p<0.001)). These experimental results demonstrate the high potential of BiTNet for use in clinical settings.

Transmission of oral microbiota to the biliary tract during endoscopic retrograde cholangiography.

BACKGROUND: Endoscopic retrograde cholangiography (ERC) possesses a translocation risk of microbes to the biliary system. We studied bile contamination during ERC and its impact on patients' outcome in a real-life-situation. METHODS: Ninety-nine ERCs were analyzed and microbial samples were taken from the throat before and from bile during ERC and from irrigation fluid of the duodenoscope before and after ERC. RESULTS: 91.2% of cholangitis patients had detectable microbes in the bile (sensitivity 91%), but the same was true for 86.2% in the non-cholangitis group. Bacteroides fragilis (p=0.015) was significantly associated with cholangitis. In 41.7% of ERCs with contaminated endoscopes these microbes were found in the bile after the procedure. Analysis of duodenoscopes' irrigation liquid after ERC matched the microbial bile analysis of these patients in 78.8%. Identical microbial species were in throat and in bile samples of the same ERC in 33% of all cases and in 45% in the non-cholangitis group. Transmission of microbes to the biliary tract did not result in more frequent cholangitis, longer hospital stays, or worse outcome. CONCLUSIONS: During ERC bile samples are regularly contaminated with microbes of the oral cavity but it did not affect clinical outcome.

Low vs Standard-Dose Indocyanine Green in the Identification of Biliary Anatomy Using Near-Infrared Fluorescence Imaging: A Multicenter Randomized Controlled Trial.

BACKGROUND: Near-infrared fluorescence imaging using intravenous indocyanine green (ICG) facilitates intraoperative identification of biliary anatomy. We hypothesize that a much lower dose of ICG than the standard decreases hepatic and background fluorescence and improves bile duct visualization. STUDY DESIGN: In this multicenter randomized controlled trial, 55 adult patients undergoing laparoscopic cholecystectomy were randomized to low-dose (0.05 mg) or standard-dose (2.5 mg) ICG preoperatively on the day of surgery. A quantitative assessment was performed on recorded videos from the operation using ImageJ software to quantify the fluorescence intensity of the bile duct, liver, and surrounding/background fat. Operating surgeons blinded to ICG dose provided a qualitative assessment of various aspects of the visualization of the extrahepatic biliary tree comparing near-infrared fluorescence to standard visible light imaging using a scale of 1 to 5 (1, unsatisfactory; 5, excellent). Quantitative and qualitative scores were compared between the groups to determine any significant differences between the doses. RESULTS: The bile duct-to-liver and bile duct-to-background fat fluorescence intensity ratios were significantly higher for the low-dose group compared with the standard-dose group (3.6 vs 0.68, p < 0.0001; and 7.5 vs 3.3, p < 0.0001, respectively). Low-dose ICG had a slightly higher (ie better) mean score on the qualitative assessment compared to the standard dose, although the differences were not statistically significant. CONCLUSIONS: Low-dose ICG leads to quantitative improvement of biliary visualization using near-infrared fluorescence imaging by minimizing liver fluorescence; this further facilitates routine use during hepatobiliary operations.

Efficacy and Safety of Near-Infrared Florescence Cholangiography Using Indocyanine Green in Laparoscopic Cholecystectomy: A Systematic Review and Meta-Analysis.

Background: Achieving critical view of safety is a key for a successful laparoscopic cholecystectomy (LC) procedure. Near-infrared fluorescence cholangiography using indocyanine green (NIF-ICG) in LC has been extensively used and accepted as beneficial auxiliary tool to visualize extrahepatic biliary structures intraoperatively. This study aimed to analyze its safety and efficacy. Materials and Methods: Searching for potential articles up to March 25, 2022 were conducted on PubMed, Europe PMC, and ClinicalTrials.gov databases. Articles on the near infrared fluorescence during laparoscopy cholecystectomy were collected. Review Manager 5.4 software was utilized to perform the statistical analysis. Results: Twenty-two studies with a total of 3457 patients undergo LC for the analysis. Our meta-analysis revealed that NIF-ICG technique during LC was associated with shorter operative time (Std. Mean Difference -0.86 [95% confidence interval (CI) -1.49 to -0.23], P = .007, I2 = 97%), lower conversion rate (risk ratio [RR] 0.28 [95% CI 0.16-0.50], P < .0001, I2 = 0%), higher success in identification of cystic duct (CD) (RR 1.24 [95% CI 1.07-1.43], P = .003, I2 = 94%), higher success in identification of common bile duct (CBD) (RR 1.31 [95% CI 1.07-1.60], P = .009, I2 = 90%), and shorter time to identify biliary structures (Std. Mean Difference -0.52 [95% CI -0.78 to -0.26], P < .0001, I2 = 0%) compared with not using NIF-ICG. Conclusions: NIF-ICG technique beneficial for early real-time visualization of biliary structure, shorter operative time, and lower risk of conversion during LC. Larger randomized clinical trials are still needed to confirm the results of our study.

Radiologic findings of biliary complications post liver transplantation.

Liver transplantation is a potentially curative treatment for patients with acute liver failure, end-stage liver disease, and primary hepatic malignancy. Despite tremendous advancements in surgical techniques and immunosuppressive management, there remains a high rate of post-transplant complications, with one of the main complications being biliary complications. In addition to anastomotic leak and stricture, numerous additional biliary complications are encountered, including ischemic cholangiopathy due to the sole arterial supply of the bile ducts, recurrence of primary biliary disease, infections, biliary obstruction from stones, cast, or hemobilia, and less commonly cystic duct remnant mucocele, vanishing duct syndrome, duct discrepancy and kinking, post-transplant lymphoproliferative disorder, retained stent, and ampullary dysfunction. This article presents an overview of biliary anatomy and surgical techniques in liver transplantation, followed by a detailed review of post-transplant biliary complications with their corresponding imaging findings on multiple modalities with emphasis on magnetic resonance imaging and MR cholangiopancreatography.

Percutaneous Cholangioscopy for the Diagnosis and Management of Biliary Pathology in Pediatric Patients: A Single-Center Experience.

Transhepatic percutaneous cholangioscopy (PC) can be used for the diagnosis and treatment of biliary pathology. It allows for direct visualization of the biliary system to identify pathologic changes, perform biopsies, and treat biliary obstruction. The effectiveness and safety of PC in adults have been established. However, the data on the use of PC in pediatric patients are limited. In this case series, the outcomes in 4 pediatric patients (3 girls; mean age, 4 [range, 1-8] years) who underwent 6 PC procedures were examined. Three out of the 6 (50%) PC procedures were performed for diagnostic visualization of the biliary tree and/or small intestine, whereas the remaining 3 (50%) were performed for the treatment of biliary obstruction causing chronic cholestasis. The technical and procedural success rate was 100%, and no complications were encountered during or 30 days after the procedure. This study supports the feasibility and safety of PC in pediatric patients for the management of biliary pathology.

A Single Gallbladder Fold Creates a Unique Visual and Temporal Pattern of Radiotracer Accumulation on Hepatobiliary Scintigraphy.

ABSTRACT: Duplication of the gallbladder represents a variant of anomalous biliary anatomy that is rarely encountered on hepatobiliary scintigraphy. We describe the case of 76-year-old man with a gallbladder fold mimicking duplication of the gallbladder or an associated choledochal cyst on scintigraphy. Correlative imaging with CT and ultrasound helped elucidate the true anatomy. This case demonstrates the type of difficult scintigraphic patterns that can arise with variant anatomy and the necessary role of cross-sectional, anatomic imaging in unraveling such situations.

Situations That Preclude Routine Intraoperative Cholangiography.

Intraoperative cholangiogram (IOC) is a useful tool for surgeons to assess anatomy of the biliary tree and diagnose biliary pathology. Many surgeons utilize cholangiography in most cases in hopes of preventing ductal injuries and are deemed routine cholangiographers. There is little data on the success rate and reasons why IOC is not performed. The purpose of this study was to evaluate the use of routine cholangiography and to determine reasons why cholangiography was not performed. 693 cholecystectomies were analyzed. Intraoperative cholangiogram was attempted in 553 (79.8%) of these cases. The success rate of performing cholangiograms in those attempted was 93.3%. Intraoperative cholangiogram was not attempted in 140 patients (20.2%) for various reasons. Although many surgeons consider themselves routine cholangiographers, there are times when IOC is not feasible. Knowledge of these reasons may help clarify indications for IOC. For most cases, routine cholangiography appears to be feasible.

Biliary Endoscopy in Altered Anatomy.

Endoscopic retrograde cholangiopancreatography (ERCP) is the standard treatment of biliary disease with high success rates of greater than 90% in patients with standard anatomy. However, alterations in upper gastrointestinal anatomy can significantly complicate endoscopic biliary intervention. The past decade has seen significant advances in the endoscopic management of patients with altered anatomy. This review article will provide tips and tricks for successful biliary access in the most common surgical alterations with a focus on the management of biliary diseases following Roux-en-Y (RY) reconstructions.